1. Technical Field
The present invention relates to a semiconductor device that includes a plurality of semiconductor pellets disposed in a row on a wafer substrate, with a scribe region disposed therebetween, and more particularly to a semiconductor device in which semiconductor element formed on a surface of the wafer substrate is hermetically enclosed in duplicate by a first and a second insulating film, and to a method of manufacturing such semiconductor device.
2. Related Art
In the semiconductor pellet, which is a semiconductor device, normally the element and electrode are covered with an insulating film to thereby protect the chip surface. To split (pelletize) the wafer into individual chips, methods such as a blade dicing and scribe breaking are employed.
During such process, the pellet suffers chipping and flaw in the vicinity of an outer peripheral edge. Here, a majority of the chipping defect takes place on a corner portion of the pellet. In the case where such chipping and flaw reaches an inner portion beyond the insulating film, moisture intrudes into the chip through the crack of the insulating film, thereby degrading moisture resistance. Moreover, in the case where such chipping and flaw reaches inside of the chip, the element or electrode may be broken, which results in loss of the essential function of the element.
It is to be noted that although the plurality of semiconductor pellets, not pelletized yet and aligned on the semiconductor substrate with the scribe region disposed therebetween, is herein referred to as the semiconductor device, the pelletized semiconductor pellets are also semiconductor devices.
Referring to FIG. 5, a first related art will be described below. A semiconductor device of the first related art includes an anti-chipping wall 3 provided along the outer periphery of semiconductor pellets 2 formed on a wafer substrate 1.
When the semiconductor pellets 2 on the wafer substrate 1 thus made up are pelletized along a scribe region 4, the anti-chipping wall 3 serves to block the progress of the chipping and flaw, to thereby protect the semiconductor pellet 2, in other words the semiconductor device (For example, refer to Japanese Laid-open patent publication No. 2008-028243).
Referring then to FIG. 6, a second related art will be described below. A semiconductor device of the second related art includes an insulating film 15 covering an inner region of a semiconductor pellet 12, which is a semiconductor device, formed on a wafer substrate 11, and corner portions of the semiconductor pellet 12 and the insulating film 15 are chamfered.
When the semiconductor pellets 12 on the wafer substrate 11 thus made up are pelletized along the scribe region 14, the corner portions of the semiconductor pellet 12 and the insulating film 15 are less likely to suffer the chipping, and therefore the semiconductor pellet 12 can be protected (For example, refer to Japanese Published patent application A-H08-293476).
In the case of the first related art, it is necessary to expand the scribe region 4 because of the presence of the anti-chipping wall 3 along the outer periphery of the semiconductor pellet 2. This results in a decrease in number of pellets that can be mounted on each wafer substrate 1.
Besides, an additional diffusion process (photo resist coat→exposure→development→film formation→photo resist removal) is required to form the anti-chipping wall 3, which leads to an increase in manufacturing cost of the wafer (material cost and wage) and to an extended production lead time.
In the case of the second related art, since a region of the semiconductor pellet 12 is exposed along the periphery of the insulating film 15, it is necessary to expand the scribe region in order to prevent the chipping on the semiconductor pellet 12.
This leads to a decrease in number of pellets per wafer substrate, as with the first related art. Besides, since the corner portions of both the semiconductor pellet 12 and the insulating film 15 are chamfered in the second example, the process of chamfering degrades the productivity.